Numerical and Experimental Analysis of the Effect of Variable Blade Row Spacing in a Subsonic Axial Turbine

Restemeier, M.; Jeschke, P.; Guendogdu, Yavuz; Gier, Jochen

doi:10.1115/gt2011-45637

Cited by 6 publications

(11 citation statements)

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“…According to the open literature, this trend is confirmed by some authors [42][43][44][45][46] but seems not general (as also reported and discussed by [41]), either for a lack of detailed data or for a case dependency in the stator wake-potential field coupling along the axial direction, in the axial gap region.…”

Section: Axial Gapmentioning

confidence: 73%

Stator-Rotor Interaction in Axial Turbine: Flow Physics and Design Perspective

Gaetani¹

2018

Aircraft Technology

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The stator-rotor interaction is an important issue in turbomachinery design when the highest performances are targeted. Different characters mark the interaction process in high-pressure or low-pressure turbines depending both on the blade height and on the Reynolds number. For small blade heights, being the stator secondary flows more important, a more complex interaction is found with respect to the high blades, where the stator blade wake dominates. In low-pressure turbines, the stator wake promotes the transition to turbulent boundary layer, allowing for an efficient application of ultra-high lift blades. First, a detailed discussion of the flow physics is proposed for high-and low-pressure turbines. Some off-design conditions are also commented. Then, a design perspective is given by discussing the effect of the axial gap between the stator and the rotor and by commenting the effects of three-dimensional design on the interaction.

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Section: Axial Gapmentioning

confidence: 73%

Stator-Rotor Interaction in Axial Turbine: Flow Physics and Design Perspective

Gaetani¹

2018

Aircraft Technology

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“…Five of the test cases are single-stage turbines and two are 1.5 stage machines. Restemeier et al 9 suggest that the second stator and the preceding axial clearance only has a minimal influence on the loss differences between the cases with different axial clearances. With this assumption, a direct comparison of single and 1.5 stage turbines is reasonable and a possible small error does not have a notable influence on the accuracy of the current analysis.…”

Section: Analysed Data and Linear Correlation Methodsmentioning

confidence: 99%

“…After this assumption, the correlations between the two parameters from Table 1 and the slopes of efficiency were evaluated. 9 1.31 0.45 Meas. Venable et al 10 4.84 1.10 URANS Chang and Tavoularis 19 -1.18 URANS Yamada et al 24 3.99 0.18 Meas.…”

Section: Analysed Data and Linear Correlation Methodsmentioning

confidence: 99%

“…In some studies, the efficiency decreases as the clearance increases. 3,8,9 However, some studies suggest a larger clearance to be more beneficial in terms of efficiency. 10,11 This behaviour is illustrated in Figure 1, where the efficiency change as a function of axial clearance is given relative to the zero axial clearance for turbines studied in this article.…”

Section: Introductionmentioning

confidence: 99%

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Importance of the vane exit Mach number on the axial clearance-related losses

Grönman

Biester

Turunen-Saaresti

et al. 2015

Proceedings of the Institution of Mechanical Engineers, Part A:

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More efficient and physically smaller axial turbine designs are promoted to lower emissions and increase revenue. The physical size and the weight of the axial turbine can be minimised by adjusting the distance between successive stator and rotor rows. The influence of changing stator-rotor axial clearance can usually have either a positive or a negative influence on the turbine performance, and the reasons for this varying behaviour are not currently fully understood. A previous study revealed several design parameters that correlate with the efficiency curve shape. However, the effects of two parameters, namely the stator outlet Mach number and the reduced blade passing frequency, still remained unclear. Therefore, a novel approach is taken to analyse the correlations between the two design parameters and the axial clearance efficiency curve shape. Several different turbines are analysed using data available in the literature, and also new data are presented. The study suggests that the stator outlet Mach number correlates reasonably well with the efficiency curve shape, and it was further linked to five loss mechanisms and the rotational speed. Although the unsteady interaction plays an important role in the loss share, the level of unsteadiness did not correlate with the efficiency curve shape.

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“…From experimental investigations conducted by Bohn et al 13 , it is furtherly known, that the use of a special miniature pneumatic probe for the correction of former probe measurements was necessary since former measurements with a larger probe had been found incorrect due to severe probe-flow interaction fudging the results for the flow field measurements in a 4-stage axial turbine. Restemeier et al 11 conducted numerical calculations as well as experimental investigations on a 1.5-stage axial turbine with very low aspect ratio and for different axial-gap configurations, in order to investigate the influence of different axial spacings between blade rows. His changes to the axial positions of the vane rows led to numerically predicted differences of Δη=0,6%.…”

Section: Introductionmentioning

confidence: 99%

Numerical assisted Design of a Variable Rotating Vane Carrier Device for Turbine Test Rigs with split Housing Structures using a Segmented Half-Ring Bearing Concept

Henke

Biester²,

Guendogdu³

et al. 2012

53rd AIAA/ASME/ASCE/AHS/ASC Structures, Structural Dynamics and Materials Conference

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The development of modern airplanes is driven by rising fuel cost and global legislation processes, reducing permissible emission outputs of CO 2 and NO X within the next years. This means ambitious goals for further design optimizations of aircrafts themselves as well as for modern jet engines powering those aircraft. For this purpose, new test methods must be developed in order to verify new engineering designs by the use of highly accurate working test facilities. The present work shows the redesign of an existing turbine test rig at the Institute of Turbomachinery and Fluid Dynamics, and the innovative engineering design of rig components allowing highly accurate experiments under robust environmental conditions. The newly designed elements of the turbine are implemented to the existing turbine housing with a horizontal interstice plane. Thus, a new split half-ring antifriction bearing concept has been developed for the use of rotating clocking vane rows for this turbine. Intensive numerical steady and unsteady CFD calculations were conducted in advance of the mechanical design phase in order to identify forces due to aerodynamic loading and optimum design parameters for the mechanical test setup and the required instrumentation. NomenclatureA = cross sectional area in the flow path c = axial chord length D = diameter h = blade height m = mass flow rate N = number of blades n = rotational speed P = electrical power output of the turbine p = total pressure r = stage reaction Re = Reynolds Number T = temperature Subscripts η = efficiency π = stage pressure ratio p in /p out ϕ = rotation angle ε = size of estimated measuremt error Greek ax = axial direction in = condition at turbine inlet out = condition at turbine outlet is = isentropic

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Numerical and Experimental Analysis of the Effect of Variable Blade Row Spacing in a Subsonic Axial Turbine

Cited by 6 publications

References 0 publications

Stator-Rotor Interaction in Axial Turbine: Flow Physics and Design Perspective

Stator-Rotor Interaction in Axial Turbine: Flow Physics and Design Perspective

Importance of the vane exit Mach number on the axial clearance-related losses

Numerical assisted Design of a Variable Rotating Vane Carrier Device for Turbine Test Rigs with split Housing Structures using a Segmented Half-Ring Bearing Concept

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